Dinoflagellate toxins in northern Baltic sea phytoplankton and zooplankton assemblages

The distribution of dinoflagellate toxins (OA, DTXs, PTXs, YTXs) in plankton communities was studied in the northern Baltic Sea during late summers of 2005 and 2006. The phycotoxins were analysed from samples that contained field collected microplankton in the size range of 20–76 μm, zooplankton collected with a net, and individually hand-picked copepods from open-sea and coastal sampling stations. Concentrations of pectenotoxin-2 (PTX2) present in the microplankton samples containing Dinophysis spp. were between 2.1 and 10.6 pg cell–1. Zooplankton net samples were positive for pectenotoxin seco acid (PTX2SA) at 10 sampling sites, and for PTX2 at two stations. The zooplankton net material contained also Dinophysis spp. cells that were the likely origin of these toxins, corresponding to 7.7–17.5 pg PTX2 cell–1. Individually picked copepods did not contain any of the phycotoxins that were included in the analyses. Yessotoxin (YTX) was found in two microplankton samples. Toxins from the okadaic acid group were not detected. Our results confirm previous observations from the study area that the presence of PTX2 is a recurrent phenomenon in microplankton communities, whereas okadaic acid presence is not.